1. Field of the Invention
The present invention relates to an image pickup apparatus detachably connecting to a light emitting device and a control method thereof.
2. Description of the Related Art
Some conventional image pickup apparatuses are provided with a strobe light emitting device mounted thereon and used for shooting of still images and have a function of resuming recording of a moving image after the moving image recording is paused to shoot a still image using the strobe light emitting device.
In this case, generally, a main capacitor for strobe light emitting internally included in the strobe light emitting device is automatically charged by a built-in charging circuit after a strobe light is emitted. In this case, there is a problem that a sound caused when the charging circuit charges the main capacitor (hereinafter simply referred to as a charging sound) is recorded on a sound recording area of a moving image recording medium.
To solve this problem, a variety of techniques have been proposed in Japanese Laid-Open Patent Publication (Kokai) No. 63-151279 (hereinafter referred to as prior art document 1). A video camera having a still camera described in prior art document 1 prevents a charging sound from being recorded by muting an audio signal during charging of a main capacitor. Further, according to prior art document 1, while the main capacitor is being charged, the amplifier gain of the audio signal is reduced so as to lower the recording level of the audio signal including charging sound.
Further, according to prior art document 1, a signal component having the same frequency as that of an oscillation sound generated during charging is removed. Further, according to prior art document 1, an audio signal previously registered in a memory is recorded together with a moving image during charging.
Furthermore, in recent years, a strobe light emitting device has been proposed in which an oscillation frequency of a charging circuit in the strobe light emitting device is set outside an audible band. In a case where such a kind of strobe light emitting device is mounted on an image pickup apparatus which can shoot a still image as well as recording a moving image, a charging sound of a charging circuit in the strobe light emitting device is not recorded even if the strobe light emitting device is used to shoot a still image during a pause of recording of a moving image and then the moving image recording is resumed.
However, conventional image pickup apparatuses have the following problems. First, if audio signals are muted during charging as described in prior art document 1, the audio signals cannot be recorded until charging of the main capacitor is completed after a still image is shot.
In addition, if the recording level of audio signals is lowered as described in prior art document 1, the sound level of reproduction is unnaturally varied because the recording level of audio signals is low until charging of a main capacitor is completed after a still image is shot.
In addition, a technique for removing a signal component having the same frequency as that of a charging sound as described in prior art document 1 can be used only in a case where the frequency of the charging sound is known, and therefore cannot be applied to a wide variety of strobe light emitting devices.
In addition, in a case where an audio signal previously registered in a memory is recorded together with a moving image during charging as described in prior art document 1, a sound from a photographic subject cannot be recorded during the charging.
Further, if the oscillation frequency of a charging circuit is set outside an audible band, a charging sound is not recorded even in a case where a still image is shot during recording of a moving image and then the moving image recording is continued.
However, in the case of this technique, users who benefit from this technique are limited because the oscillation frequency of the charging circuit of a strobe light emitting device owned by a user is not always set outside an audible band.